Optical glass



United States PatentOfi 2,777,774 Patente 1957 OPTICAL GLASS Gustav Weissenberg, Marburg (Lahn), and Norbert Meinert, Munchhausen, Germany, assignors to Ernst Leitz, G. in. b. H., Wetzler (Lahn),'Gennany, a corporation of Germany No Drawing. Application January 21 1953 Serial No. 332,558

Claims priority, application Germany February 26, 1952 2 Claims. (Cl. 106-47) Our present invention relates to optical glass and more particularly to a glass of unusually low dispersion.

many years.

The new crown glasses of our invention are obtained by the common melting of a mixture of at least one In for the purpose from the group of elements consisting a carbonate, lithium carbonate.

In Table 3 again a metaphosphate, magnesium metaphosphate, an oxide, namely boric oxide, and two carbonates, lithium carbonate and barium carbonate, are used.

lanthanum, the periodic system, is added.

In Table 7 are shown mixes containing magnesium metaphosphate, barium orthophosphate and lanthanum oxide.

Table 8 shows that a combination of a metaphosphate and an orthophosphate with oxides and carbonates leads to equally good values.

In Table 9 are shown two orthophosphates with a metaphosphate and moreover an addition of lanthanum oxide.

improved. For stabilizing, it has been found of value to use'phosphates of the elements, boron, lanthanum and indium.

Table 11 shows glasses with boron phosphate.

Table 12 shows glasses with lanthanum phosphate and indium phosphate, respectively.

The compositions given in the examples can be varied in wide measure-naturally they establish no bounds for Table 1 [In percent by weight.]

' Melt No. Mg(POa)z 141003 .11.. v

Table 2 [In percent by weight.]

A/Ielt N o. lVIg(P0 )g B103 LizCO3 n... v

' 86. 2 12. 9 0. 9 1. 5223 69. 2 85. 8 12. 9 1. 3 1. 5231 69. 5 85. 4 12. 9 1. 7 1. 5249 69. 5 84. 5 12. 7 2. 8 1. 5286 69. 5 6/ 80.0 12.0 8.0 l. 5360 69. 7 76.0 11. 4 12. 6 1. 5429 a 69.8 R 74. 0 11. 2 14.8 1.5483 69. 4 I 69.0 l0. 4 20. 6 1.5533 68. 7 64. 5 9. 7 5. 8 1. 5559 68. 5 60. 5 9. 2 30. 8 1. 5558 68. 3 57. 1 8. 6 34. 3 1. 5567 67. 5

Table 3 [In percent by weight.]

Melt N0. Mg(POa)z B203 H200: B2003 n Table V v Table 10 {111 percent by weight} A percent by weight] Meu'No 83G 0 v Melt N0. ME(P S)S S11(P04): L810 141300: 11,, I)

. Tablel} {In percent by weight.]

.ivieimo. MgGEOi): 133430.). 111.0. 11. r 3 M31100. M3301), B31000, 3P0; 813F 0 n. v

R144 45.5 45.3 n 9 1.5751 67.0 B151 41.7 41 .1 16.6 1.5710 00.1 was 1115s-. 33.4 =.3s..4. ;23.2 1.5000 -68.0

[Ln-paicent by-weightJ In "11. M61715 NO. MflPosh BBzQPODg BzOt B '0, v i. percentb? ii t] W317IR152.-.- 38.5 38.3 15.3 7.7 1.5311 68:3 25 Mgaom In]? R153 .7 35.1 35.1 14.3 14.3 1.5923- 000 Table7 [111 percent by weight} T v g I V I o Melt B =9 0 Having; descnbedour invention; what we 0131131151 r I V r 1. Optical crown glass the; glass forming constituents of 321% 231% 221% which consist-essentiallylofat least one metaphosphate of 1 6103 63 2 35 thegroup consisting, of magnesium, calcium. strontium and barium, boron trioxide and at least one. carbonate of the group .eonsisting of; magnesium, calcimn, strontium, barium and lithium and being the heat reaction productv of a'batch having from ,57 .to, 86% by weightof said 1 Melt 1 r a 40 metaphospnateand-frorn bout 8.6% to abont'1'2.6% of No. boron trioxideand from 0.9% (034.4% of sald carbonate g g-3 32-8 22-2 2. Optical;crown glass;the.g1ass 'f ormingconstituents 5 1 1 113' 5759 1 of-which consist essentially 01.1113. heat; reaction products $1 -6 gw 5 52 ag-$ eta-batch having from ,62%' to /4% by weight of magn 1 13815 nesium, metaphosphate; 6.2%..10' 7.4% vby weight of g-3 1 23%;. 3g? lithiumcaxboflate; 7.4% "to 21. 9%. by weight otibgrium 3 1 :7 1 1: 7 carbonate and 9.4%;10 1.112%;tbY :Wfiigbt ofboron trioxide.

v Refexences Cited-mike file, of thispatent Table9 V V PATENTS 7 imvewefltbyweight-l j j 2,278,501 Tillyerretal. Apr. 7, 1942. 2,294,844 Gelstharp g- ,Sept. 1, 1942. MgflOQ; 511C904); BBI(PO)1 L810: 11, u I 

1. OPTICAL CROWNS GLASS THE GLASS FORMING CONSTITUENTS OF WHICH CONSIST ESSENTIALLY OF AT LEAST ONE METAPHOSPHATE OF THE GROUP CONSISTING OF MAGNESIUM, CALCIUM, STRONITUM AND BARIUM, BORON TRIOXIDE AND AT LEAST OEN CARBONATE OF THE GROUP CONSISTING OF MAGNESIUM, CLCIUM, STRONTIUM, BARIUM AND LITHIUM AND BEING THE HEAT REACTION PRODUCT OF A BATCH HAVING FROM 57% TO 86% BY WEIGHT OF SAID METAPHOSPHATE AND FROM ABOUT 8.6% TO ABOUT 12.6% OF BORON TRIOXIDE AND FROM 0.9% TO 34.4% OF SAID CARBONATE GROUP. 